Some people believe (or claim to believe) that if God does not exist, then there are no objective moral truths (e.g., truths about what we are morally obligated to do or refrain from doing). This claim is false as the following argument shows:

(1) Torturing a child causes the child to experience severe suffering.
(2) Torturing a child violates the child’s consent (that is, it is not possible for the child to rationally consent to being tortured).
(3) That torturing a child causes severe suffering is a reason to not torture children.

(4) That torturing a child violates the child’s consent is a reason to not torture children.

Thus,
(5) There are reasons to not torture children
(6) Torturing a child would cause severe suffering even if God does not exist.
(7) Torturing a child would violate the child’s consent even if God does not exist.
Thus,
(8) There would be reasons to not torture children even if God does not exist.
(9) These reasons are so powerful as to be overriding (that is, they are stronger than and cancel the force of any other reasons that might exist that count in favor of torture).
(10) These reasons also concern the welfare and autonomy of persons.
Thus,
(11) There are overriding reasons, concerning the welfare and autonomy of persons, to not torture children, and that exist even if God does not exist.
(12) If there are overriding reasons, concerning the welfare and autonomy of persons, to not engage in some action, then this action is morally wrong.
Therefore,
(13) There are some actions that are morally wrong even if God does not exist.